Impact of electron-LO-phonon correction and donor impurity localization on the linear and nonlinear optical properties in spherical core/shell semiconductor quantum dots

In the present work, the linear, third-order nonlinear and total optical absorption coefficients as well as relative refractive index change have been calculated in the case of GaAs/AlAs core/shell quantum dot, taking into account the effects of the interaction with LO-phonon and the presence and localization of a donor impurity center. Our calculations are performed in the framework of the effective mass approximation and the numerical results are obtained by using a variational method and an infinite confining potential. The results are presented as a function of the incident photon energy. It has been seen that: (i) the polaronic effect causes a redshift of the nonlinear optical coefficients associated to light absorption and relative refractive index change (ii) the polaronic effect is enhanced with the decreasing of quantum dot radius (iii) The donor position effects are particularly significant when the Coulombic center is located at the radial positions D=(RS+RC)/2 and D=RS of the shell, where RC and RS the core and the shell radius respectively.